The invention relates to a hinge-lid box for cigarettes, comprising a box part and lid, which have side tabs and lid side tabs which are connected to one another by glue and are intended for forming side walls of the box part and of the lid. The invention also relates to a process and apparatus for gluing packaging material, namely material webs, blanks or folding tabs of not-yet finished packs, during the production of these packs.
The gluing region for packaging material, in particular blanks made of paper or (thin) cardboard, in order to connect folding tabs to one another or to other parts of the pack is a sensitive region of a packaging machine. In particular in the case of packaging machines for cigarettes, the operation of applying glue to blanks poses problems due to the high output of such packaging machines and the short cycle times which result therefrom.
In the production of hinge-lid boxes (hinge-lid packs), applications of glue are to be applied to a plurality of regions of the thin-cardboard blanks. It has already been proposed for spot-like applications of glue to be applied to the non-folded, that is to say planar, blanks from above by glue nozzles producing spots of glue at selected positions by way of short spraying or injecting cycles.
In order to form side walls of the box part and of the lid of this type of pack, folding tabs, namely in each case inner and outer side tabs and lid side tabs, are to be connected to one another by glue. During an end phase of the production of the hinge-lid box, outer side tabs and lid side tabs are directed sideways in a horizontal position and have the inner side which is to be glued oriented downwards. Up until now, these outer side tabs and lid side tabs have been glued by glue wheels or glue discs, which are provided with a layer of glue on the outer circumference and transfer strip-like applications of glue by butting against the folding tabs during transportation of the packs. The glue discs or wheels form part of a glue assembly which, since it operates as has been described, requires a high level of maintenance and, moreover, is susceptible to malfunctioning.
The object of the invention is to propose measures for reliable, malfunction-free transfer of complex applications of glue to packaging material, with the packaging machine having a high output capacity.
In order to achieve this object, the hinge-lid box according to the invention is configured, as far as the formation and arrangement of applications of glue in the region of side walls and lid side walls are concerned, such that the (outer) side tabs and lid side tabs are connected to one another by narrow, continuous strips of glue running in the longitudinal direction of said tabs, preferably by in each case two parallel strips of glue.
The prior-art applications of glue in the region of the abovementioned folding tabs are designed such that the application of glue is constituted by rectangular areas of glue in a row. This structure of the application of glue is achieved as a result of the configuration and operation of the glue discs, or glue wheels, provided with corresponding depressions. Instead, the invention forms thin, uninterrupted, that is to say continuous, strips of glue.
An important issue of the invention is the application of the preferably strip-like applications of glue to the folding tabs of the blanks or not-yet finished packs, but also to non-folded blanks or continuous material webs. The process according to the invention is characterized in that preferably strip-like applications of glue are transferred onto the packaging materialxe2x80x94material web, blank or folding tabs of not-yet finished packsxe2x80x94by relative movement with respect to a glue dispenser, in particular glue nozzles, the packaging material butting against a glue dispenser in the region of the glue transfer.
Accordingly, in the case of the process according to the invention, applications of glue, in particular strips of glue, are transferred by contact with the packaging material with the mouth of a glue nozzle, the packaging material being in contact with the nozzle mouth as it is drawn beyond the glue nozzle, which is preferably fixed. The limitation of the application of glue in the movement direction of the packaging material is defined by the opening phase of the glue nozzle or by the duration of the feed of glue. Accordingly, the glue nozzle is controlled in terms of the opening phase or in terms of the feed of glue, to be precise in dependence of the speed of the packaging material, on the one hand, and on the sought-after dimension of the strip of glue in the movement direction, on the other hand.
A process-specific special feature is realized when the packaging machine is operated at diminished cycle rates, in particular when the packaging machine is started up. During this operating state, the glue assembly is driven in a cyclic manner, i.e. glue is fed to the glue nozzles in a intermittent or pulsed manner. For this purpose, a valve or shut-off element, which can be controlled in the corresponding pulsed or intermittent manner, is arranged in a glue line which supplies the glue nozzle.
Furthermorexe2x80x94depending on the operating state of the packaging machinexe2x80x94the feed of glue can be regulated by altering the pressure acting on the glue. A relatively low pressure is exerted on the glue in the case of a relatively low conveying speed of the packaging material and a relatively high pressure is exerted on the glue in the case of a correspondingly higher conveying speed, this pressure being exerted preferably by a pump for the feed of glue.
The apparatus according to the invention for gluing packaging material, in particular blanks, comprises a stationary glue assembly in the movement path of the packaging material, to be precise beneath said movement path. The glue assembly comprises preferably a plurality of nozzles for applying a plurality of parallel strips of glue, it being the case that the packaging material moves via the upwardly directed nozzle mouths and can be pressed against the nozzle mouths by a pressure-exerting element at least during the glue transfer.
Further details of the invention relate to the process for applying glue and to details of the apparatus, including a monitoring unit for checking the correct formation of the applications of glue. An exemplary embodiment for the configuration of a blank and details of the apparatus are explained in more detail hereinbelow with reference to the drawings, in which: